350 or LS

I am new to this forum and to "car stuff" too. I don't know all the proper terms so bare with me and please forgive my ignorance.

I took on the responsibility of getting my dad's 77 C10 short bed back on the road. He gave it to my uncle in the late 80s early 90s and he proceeded to destroy it. It has been flooded. The bed is rusted through and the engine is shot. The big question I am trying to decide is whether or not I should go with a 350 or LS engine. I have no big desire for it have tons of power, maybe spin the tires here and there. I just want to be able to get in it and go where I need when I am home. Getting decent gas mileage would be wonderful. The local community college has agreed to take it on as a project for the students. They will do all the work, I just need to supply the parts. I have done lots of reading trying to figure things out but seem to be getting nowhere. The 350 will bolt right on nothing needs to be changed, but the gas mileage is horrible and the tech is so old. With an LS it will just fire right up, it will just run nice and smooth. However, it requires so many modifications. That is the gist of what is going on, any help would be great.

Which engine would you guys suggest and why?

350. That is what belongs in that truck. Bolts right in, no computer or sensors. JMO, many others will speak differently.....

Cruck said:

I am new to this forum and to "car stuff" too. I don't know all the proper terms so bare with me and please forgive my ignorance.

I took on the responsibility of getting my dad's 77 C10 short bed back on the road. He gave it to my uncle in the late 80s early 90s and he proceeded to destroy it. It has been flooded. The bed is rusted through and the engine is shot. The big question I am trying to decide is whether or not I should go with a 350 or LS engine. I have no big desire for it have tons of power, maybe spin the tires here and there. I just want to be able to get in it and go where I need when I am home. Getting decent gas mileage would be wonderful. The local community college has agreed to take it on as a project for the students. They will do all the work, I just need to supply the parts. I have done lots of reading trying to figure things out but seem to be getting nowhere. The 350 will bolt right on nothing needs to be changed, but the gas mileage is horrible and the tech is so old. With an LS it will just fire right up, it will just run nice and smooth. However, it requires so many modifications. That is the gist of what is going on, any help would be great.

Which engine would you guys suggest and why?

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Compare milage on vortec suburban vs. ls suburban. Almost identical. Do injected SBC trucks start right up and drive? Yes. Did millions if people count on 350 burbs and Escalades as mom and kid transportion? Yes. SBC is reliable and not horrible on fuel with modern engine management. Buy a 5.7 lt1 roadmaster (lt1) swap in the engine,transmission ecm and engine harness. Cheap fuel injection,good engine management,and it's a bolt in. Or swap in a complete TBI or Vortec drivetrain. Including engine management.If your real goals are just easy,reliable,and decent mpg. If just an occasional driver stick a good carbureated 350 in it and call it a day. The difference in cost will pay for a lot of fuel. And people counted on carbureated 350s for decades,to run business, get to work, cross country on vacations. We still had vehicles we could count on ,before LSs

350 . Just say No to computers and No to LS

If your goal is just a fun weekend/occasional cruiser and you wanna be budget friendly, a warmed over 350 would definitely be the cheapest and easiest route. That, paired with a good overdrive transmission and a rear gear matched to the power band of the engine would make a fun little truck.

I'll give you a little insight into the LS side since that's what I did with my truck. It's a ton of fun, the drivability and fuel mileage is better than a small block could ever dream of being and is a pleasure to drive. But it ain't cheap. There's lots of ways you can go this route, cheap/budget build or high end/expensive. I'm somewhere in the middle. Here's a rough breakdown off the top of my head:

- LH6 5.3 (aluminum block, flat top pistons, 799 heads, TBSS intake, the hottest 5.3 available at the time out of an Envoy Denali/V8 Trailblazer)/4L65E - $3,000
- BTR cam, pushrods, lifters, engine gasket and seal set, etc - $800
- 3200 stall torque converter - $500
- Swap harness (PSI Conversions, I'd use BP Harness next time) - $800
- Driveshaft - $400
- Rear axle parts (3.90 Richmond gearset, Yukon Duragrip posi, all seals/bearings/races, setup kit, 30 spline axles, T/A girdle, all from Quick Performance) - ~$1100
- Rear axle build labor - $500
- Longtube headers (Speed Engineering) - $350
- Exhaust (mufflers and labor of the shop) - $450
- Engine/trans mounts, radiator fan shroud (from Tejas Steelworks) - $350
- Big block radiator (Spectre) - $180
- 2 Spal fans (middle CFM rating) - $350
- Tune - $500
- Fluids/miscellaneous - $800

That's 10k right there just to get the truck on the road. You could save ~800-1200 by sticking with the stock cam/torque converter but still, an LS swap isn't cheap. You could buy a wrecked doner, send off the stock harness to be cut down and be in it way less but you'd still see 5 grand pretty quickly.

But I'll tell ya this, I've put 45k miles on the truck now with trips all over the southeast and twice now from Ga to Az and back for Dino's Git Down, getting 18-22mpg and I still love every second of driving this thing. Worth every penny.

My 350 was tired and worn out, took it out and had the shop bore it and made a 383 stroker. I love the way carb engines sound at idle. I did think about doing a LS swap, but making a 383 came out way cheaper then doing a LS swap and way easier. But honestly its your truck, do what you want.

I'm a fan of LS engines, but in this situation, I think you're best off with a rebuilt 350 and a carb, unless the tech school wants/needs to do something more modern, in which case a stock 5.3 or 6.0 (LS) is what you're after. Get the transmission that came behind it, have it rebuilt (if it's a 4L60e, get it rebuilt to 4L70e specs as much as reasonably possible), and get a reputable aftermarket harness/stock computer, buy an '87 fuel tank and sender, add a pump and redo the lines etc.

Rebuilding the 350 or whatever core you have will be a reasonable good option for the school, but opens you up to the skills of the kids and the oversight of the teacher. A crate motor is the simple button, but will cost more most likely (depending on your machine shop costs). Going to a 383 (which involves swapping the crankshaft, pistons, and rods) is a good way to get more power from it, but will affect your MPG's.

Either way you go, this is a great resource site, tons of info available with the search, and if you can't find it, tons more available by asking.

350 SBC. LS swap is cool, but a lot involved for not much better gas mileage. Don't make it more difficult than it already is going to be getting that old square back on the road.

Budget and capability of the folks doing the work is key. As is how many miles you plan on putting on it.
From my point of view, LS swap for a few reasons.
1 fuel mileage if you plan on alot of miles and going as far as swapping in an OD trans.
2 fun factor. You’ll spend as much or more from my research building a 350 small block that will rev like a stock LS and have the power that a LS with bolt ons will have.
3 being unique. IMO LS swap is still unique and not the norm.

Downsides are it is more complicated as is your situation of what the volunteers are willing to do for you.
I’m in the active contemplation phase of what I ultimately want to do with the powertrain in the 77. Difference being, it has a turn key new 350 under the hood and a fresh rebuilt TH350 that I could drive from here to your house with nothing but a gas card.

All that said, based on your first post, the bigger picture question is what is the truck going to take to get it to where you want it to be?
When you throw out terms like trashed, flooded, rusted out, that sounds like the trifecta of either becoming a parts truck, recycled metal or a complete restoration.
I view “projects” like this in 3 categories.
The “clean, runs, decent shape” only need “100 things”.
The “projects” need “1000 things.”
And a vehicle as you described needs “everything.”
As you’re admittedly new to this without any past frames of reference, this truck sounds like somewhere between the hypothetical 1000 things and everything. Simply because your untrained eyes are able to identify several major issues.
Quick numbers, bought the 77 this past year. Basically as it sits now. The PO resurrected it from 20-30 years of sitting, not flooded, not trashed, not rusted and all in one piece, fired up and limped it home. He is not a mechanic. He gave me $15k in receipts for a truck that has a reman stock engine with new accessories (mostly), stock rebuilt trans and new tires and brakes. Just a quick summary of how costs add up and how they add up to 3x as much when you hire out the work. That $15k includes $0 for body, paint, electrical, interior. It’s nothing but drivetrain and running gear work. And that work was done to a truck that was already in great original shape. IE no surprises or difficulties.
And he never even changed out the original diff fluid! lol
Not trying to dissuade you here, but rather get you to think about the whole process and not just the vroom vroom under the hood. That’s actually the easy part.

350 for the win

If your truck is in good shape, LS swap is cool now, but 20 years from now it will be a classic truck with the wrong engine.

That's a tough one. Kinda like manual brakes or power brakes, I mean they both get the job done.

SquareRoot said:

That's a tough one. Kinda like manual brakes or power brakes, I mean they both get the job done.

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You know, there's a lot of autocross guys that run an LS and manual brakes. What do you think about that? Lol

bucket said:

You know, there's a lot of autocross guys that run an LS and manual brakes. What do you think about that? Lol

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It's better than Manuel brakes

Based on your experience level, and the expertise of your crew, a mild 350 build would seem to make the most sense. Lots of info and all kinds of parts available to fit any budget.

The weakest points of the early GM 350 are poor flowing smog-era cylinder heads, low compression, and old design flat tappet cams that don’t mix well with modern oils. All the early 350’s have these limitations, even the mythical Corvette engine that someone's buddy wants to sell you for $***.

My suggestion is to start out with a Vortec 350 (it was the stock engine in mid 90’s and up), or plan to swap heads to use Vortec iron heads or a budget aluminum head. Also plan to use a roller cam (Vortec 350 already has one), or a roller cam conversion. Using that as a basis, it’s easy to build a reliable 325-350 HP 350 with very good street manners.